After thinking about it for a bit I decided to try a different approach with the G.I. wiring. First I mapped out where the wiring needed to go on the new playfield with a black marker, using the old playfield as a guide. Like so:
Then I made a second pass, stapling down wire as I fed it directly off the spool. When I reached a lamp socket I cut the wire and stripped off about an inch, and then started laying down another piece to travel to the next socket.
Then, I made a third pass, mounting and soldering all the lamp sockets, including the pop bumper lamps. Here it is with the G.I. almost all done (plus some lamp circuit boards and miscellaneous parts that were trivial to transfer):



















